Process of treating concrete aggregate



June 112, H928. 11,458,387 c. L. BOURNE PROCESS OF TREATING CONCRETEAGGREGATE Filed M y 17 1920 Patented June 12, 1923.

arren stares laiifidiiti CHARLES LUTHER BOURNE, or ivrrnnnaroms,MINNESOTA.

PROCESS OF TREATING CONCRETE AGGREGATE.

Application filed May 1"], 1920. Serial No. 381,925.

T 0 aZZ whom it may concern:

Be it known that 1, CHARLES LUTHER Bonnnn, a citizen of the UnitedStates, residing at Minneapolis, in the county of Hennepin and State ofMinnesota, have invented certain new and useful Improven'ients inProcesses of Treating Concrete Aggregate; and I do hereby declare thefollowing to be a full, clear, and exact description of the invention,such as will enable others skilled in the art to which it appertains tomake and use the same. 1

My invention has for its object to provide an improved process ofremoving the softer or less tough particles from the harder or toughparticles of substances, such as gravel; and to such ends, generallystated, the invention consists of the novel treatment or steps ofmanipulation hereinafter described and defined in the claims.

Especially, the invention is directed to means for insuring betteraggregate for concrete by removing from gravel all of the softer or lesstough particles, such as soft rock, shale, and dried clay or dirt.

My improved process consists in projecting the uncleaned aggregate,containing all of the harder and softer particles, against a hardsurface at such high velocity, or otherwise subjecting the same to animpact so that the impact produced will finely break up or pulverize allof the relatively soft or less tough undesirable substances or in otherwords, the substances having a co-efficient of hardness below a certainstandard, such as soft rock, shale, dried clay or dirt, but will leaveintact, or, in any event, not break up to any considerable extent, norpulverize the hard or tough substances or thus having a co-eflicient ofhardness above a certain standard. This step of the process reduces theaggregate to such a condition that all of the soft or less toughsubstances can be re-v moved and separated from the harder or toughersubstances by a screening action, or otherwise, as by washing orairblast. The extent to which the softer or less tough substances will befinely broken up or pulverized may be varied, first by varying the forceof each impact, and second, by varying the number of impacts orrepetitions.

The harder or tougher substances thus left in the cleaned aggregatewill, of course, produce the highest possible grade of concrete, such asrequired for pavements, or any concrete work that is subject to highstresses.

One of the chief causes of rapid Wear or dis.-

integration of concrete pavements is due to wearing away by the actionof abrasion or the weather, of exposed relatively soft or less toughparticles. v

The aggregate may be projected, as stated,

in different Ways, as, for example, by ceni trifugal force, by gravity,or bydirect force.

One form of the. apparatus suitable for performing the process abovedescribed is illustrated in the accompanying drawings wherein likecharacters lndicate like throughout the several views.

Referring to the drawings:

Fig. 1 is a vertical section illustrating the apparatus; and i Fig. 2 isa transverse section taken on the line 2-2 of Fig.1. I

The numeral 3 indicates a larger outer slightly inclined drum,preferably, of sheet metal. This drum, at its lower portion, is

parts shown as provided with two axially spaced spider-like heads thatare rotatably mounted on an inclined shaft 5, which latter, at itslowerend, is journaled in a fixed bearing pedestal 6, and at its upper end isjournaled to a fixed bearing pedestal 7. Atits upper or receiving end,the outer drum 3 isirigidly secured to an inwardly projected deflectingcone 8, which, inturn, is rigidly secured to the arms of a spider-likehead 9 carried by a sleeve 10 rotatively mounted on the shaft 5.Approximately-in line with the defleeting cone 8, the drum 3 is shownasprovided with axially spaced outstanding flanges 11 that afford anannular channel into which the lower end of a fixed hopper 12 projectsfor the delivery of the aggregate into said drum 3 through closelyadjacent circumferentially spaced ports 13.

VVoi-king within the outer drum 3 and so cured to and carried by theshaft 5 is an inner drum 14 that extends through the contracted portionof the deflecting cone 8, at its upper end, but at its lower end,terminates short of the inner of the two headset. This inner drum 14; isprovided with circumfereir tially spaced longitudinally extended heavyhard metal. or steel impact cleats 15. The outer drum 3, on its innersurface, is provided with longitudinally extended circumferentiallyspaced similar impactcleats 16. At intervals between said cleats 16, thedrum 3 is provided with internal lifting flights. 17. That portion ofthe outer drum 3 that is between the heads 4, is shown as perforated solli) as to I afford-Kan larger pulley 27 which, as

' into the receiving end of the a it drum '14.

c theimpacting aiiiiular screen 18 that will deliver into a receivinghopper 19. The numeral 20 At its upper end, the shaft provided with apulley 23that is driven through a belt adapted to lb'edriv'en. atvariable speed under the vcontrol of-a rheostat 26.

The sleeve 10 is provided with a relatively shown, v is. driven througha belt% from another electricmotor--29- that is adapted to be driven atvarispeed of the respective motors. However, it

will be understood thatv this apparatus is nly one ,of the many formsthat may, be

used for'p'erforming-the process.

Describin the apparatus illustratedin its use, forperformingtli-eprocess,-it willjfirst be noted that the" aggregate, willbe delivered outer drurn and, onto the receiving end of, the. inner Bythe rotation of, said inner druin at highfsjpeed, the-aggregate will bethrown o'utward by centrifugal force against plates 16- ofrthe outerdrum and the'require'd impacts will be produced. These impacts will berepeated over and over a ain as the a t re rate' r'aduall works D t) D bdownw rd to the delivery. or lower end of the inner drum. The aggregatethrown against the inner surface of the outer drum will, by. the liftingflights '17, be carried upi i walr'd over [and over again, anddropped'by centrifugal force onto the cleaned surface- 1 of the innerdrum, thus the aggregate will-be-sub'ject to the repetitions of thepacts already noted.

The beveled faces ofthe cleats 16 also assist in returning theaggregateover and over again onto the cleated surface of the: inner dru'rn'yandas the aggregate falls back indicates a non-rotary head that isfixed tothe'ljr'aelieflG' and closes the lower ,end of the drum 3-, except for adischarge passage 21 that delivers into discharge spout 22.

against said inner drum, the cleats 15, striking the same at highvelocity, will also produce impactswhich assist in breaking uptheso-fter or less tough substances.

After the aggregate has been treated, as described, it is" deliveredonto the rotating annular screen 18, and, under rotation thereof, thepulverized orfinely broken particles will be sifted out and intothehopper 19, while the harder and larger particles will be carried onandfdelivered into the discharge spout 22. Y

may be varied by varying the inclination of the drums, it being, ofcoarse, understood that the greater the inclination of the drums,

the more rapid will be the progress of the aggregate through the outerdrum, and hence, theless the number of impacts; the crushing action maybe; varied'by varying the speed of rotation of the innerdra n However,as already indicated, the process may be performed by various otherforms of apparat' What I claim is;

1. They process of treating. aggregate material. compris ng gravel orother rock parwith softer particles, such as soft rock, shale, clay,dirt andthelike', which consists in subjecting said material? to ticlesassociated repeated impacts between relatively moving surfaces,regulatingsuch impacts in number and force so asto break up part cleshaving The number of impacts us,or by any other suitable means; I,

a vco-efficient of hardness less than a certain standard but not tobreak up the particles having a co-efficient of hardness greater thansaid standard, anddthen separating the broken-up particles from theunbroken particles to produce an aggregate material new ing a standardofhardness suitable for cori- I crete, v 2. The process of treating an:aggregate material comprising, gravel associated vwith r ds t cl y,

P cle o .sqfi t hei and other soft particles, which consists nprojecting said inaterial'by centrifugal force and producing impact-sthereon by. moving surfaces so regulating I said impacts as to break upthe particles of soft rock,',shale,

clayand other so ft material, bueaettq A break up thehar'd particles,then separating the broken-up particles from the hard'particles toproduce an aggregate of hard particles suitable for concrete. y l

In testimony whereof IfifiiX s'i J tters; CHARLES LUTHER BOU' NE.

